The present invention relates to a method and system for monitoring the operating condition of industrial machines such as large-sized presses and machine tools.
Since an industrial machine such as a large-sized press used in production lines for various types of molded articles is placed in the most upstream position of a line, if a failure occurs in the industrial machine, the whole line will be stopped, resulting in great loss. Recently, due to the increasing demands for better performance and improved man-machine interface, mechatronization proceeds rapidly and more and more so-called xe2x80x9cblack boxxe2x80x9d parts are incorporated in such an industrial machine. Under such a situation, maintenance requires various knowledge and experience and, in fact, maintenance staff on a user side can no longer cope with. Therefore, it becomes essential for makers to establish a prompt maintenance support system for troubleshooting. In particular, the development of a system, which enables preventive maintenance with accurate acquisition of machine conditions from a remote point, is long waited.
The following techniques are known as prior art associated with machine fault diagnosis.
(1) Japanese Patent Publication (KOKAI) Gazette No. 3-154846 (1991)
The technique disclosed in this publication relates to a fault-diagnostic system for finding the cause of a fault if a target for control in a sequence control system has failed. In this system, question and answer selection is done in a dialog form, with the aid of a fault tree to identify the cause of a trouble and indicate a way of repairing.
(2) Japanese Utility Model Publication (KOKAI) Gazette No. 4-113051(1992)
This technique is associated with a system for diagnosing a failure occurring in a machine based on detection of electrically detectable physical phenomena such as sound, vibration, and heat generated during machine operation. In this system, the difference between detection values obtained at two detecting positions in a machine is calculated and if the difference exceeds a preset value, it is then determined that a failure has occurred.
(3) Japanese Patent Publication (KOKAI) Gazette No. 4-361814 (1992)
This relates to looseness diagnostics, elongation characteristics diagnostics, and abnormality diagnostics for judgement on leveling, these diagnostics being adapted in a rolling system such as a rolling machine.
According to this technique, the displacement of bearing boxes for upper and lower work rolls is measured and the elongation characteristics and abnormal condition of the rolling system are diagnosed based on changes in the fluctuating waveform of the displacement of the bearing boxes relative to time.
(4) Japanese Patent Publication (KOKAI) Gazette No. 5-200658 (1993)
This relates to a production management system for analyzing the cause of a trouble which occurred in a system having a plurality of processing machines connected via a communication network. This system is designed such that each terminal unit connected to the communication network has a processing machine fault diagnostic section and a self diagnostic section.
These techniques, however, have revealed their inherent problems. Concretely, although the technique (1) is effective in finding the cause of a failure when an abnormality has occurred, it cannot preliminary detect a symptom before occurrence of an abnormality. The technique (2) is disadvantageous in that it makes erroneous detection when a noise is included in a sensor for obtaining a detection value since fault judgement done by this technique is based on information related to a certain point on a time axis. In addition, it is difficult for the technique (2) to make a judgement without data on positions before and after a detection point. The technique (3) has the disadvantage that since it is intended for use in rolling systems such as rolling machines, it is not applicable to systems which grasp, at one location, the respective conditions of industrial machines located on a plurality of lines. Lastly, the technique (4) is dependent on ON/OFF information as to whether or not each of dispersed machines is in operation and therefore cannot observe the condition of each machine in real time before a machine trouble occurs.
The present invention is directed to overcoming the foregoing problems and one of the objects of the invention is therefore to provide a method and system for monitoring an industrial machine, which enables it to quantitatively grasp the conditions of machines on dispersed lines before occurrence of an abnormality without going to the installation location of each machine so that the efficiency of machine fault diagnosis can be improved.
The above object can be accomplished by a method for monitoring an industrial machine according to a first aspect of the invention, in which the operating condition of an industrial machine is measured and recorded as continuous time-series waveform data and this waveform data is processed to be graphically displayed on the screen of a terminal unit.
According to the invention, before an abnormality occurs, the condition of a machine is recorded as continuous time-series waveform data, that is, a packet of time-series data and the recorded data is displayed on the screen of a terminal unit, so that the condition of each of the machines on dispersed lines can be quantitatively grasped at first sight from the screen and the point which requires maintenance and a way of maintenance can be properly instructed judging from the trend of changes in the waveform. In addition, since the condition of each machine can be monitored without going to the installing location of each machine, the efficiency of machine condition diagnosis can be improved and downtime due to a machine failure can be reduced.
In the invention, the recorded waveform data is preferably displayed on a terminal unit located at a remote point via a communication line. With this arrangement, the maker can provide the user with a prompt maintenance support service and proper recommendations as to maintenance positions and maintenance periods, after delivery of the machines to the user.
The invention is preferably arranged such that the normal condition of an industrial machine is preliminarily recorded as continuous time-series waveform data and can be graphically displayed on the screen of the terminal unit. Therefore, waveform data obtained under a certain operating condition can be compared to the waveform data of the normal condition to grasp the trend of the waveform data of the certain operating condition. In this way, from the result of the comparison between the waveforms of the normal condition and the present operating condition, information on machine fault diagnosis can be observed before occurrence of a failure in the machine, which enables more accurate condition diagnosis.
In this case, it is preferable to allow switching from a presently displayed screen to a diagnosis guidance screen which is used for diagnosing the abnormal condition of the industrial machine, based on the result of a comparison between the waveform data of the normal condition and the waveform data of a certain operating condition. Further, it is preferable that a presently displayed screen be switched from the diagnosis guidance screen to a screen which designates a point where a failure has occurred. This facilitates judgement on the cause of a failure and a way of tackling the failure so that there is no need to individually investigate each maintenance point but only the designated point may be investigated. This significantly reduces investigating time and maintenance time.
According to a second aspect of the invention, there is provided a system for monitoring an industrial machine, which comprises measuring means for measuring the operating condition of an industrial machine, recording means for recording data obtained from measurement by the measuring means as continuous time-series waveform data, and displaying means for processing and graphically displaying the waveform data recorded by the recording means.
The second aspect of the invention is associated with a monitoring system intended for use with the industrial machine monitoring method of the first aspect of the invention and has the same effects as those attained by the method of the first aspect.
The monitoring system of the invention preferably includes transmitting means for transmitting the recorded waveform data to a terminal unit located at a remote point via a communication line to display it on the terminal unit. In this case, the displaying means is preferably designed such that the normal condition of an industrial machine can be preliminarily recorded as continuous time-series waveform data and graphically displayed on the screen of the terminal unit, and waveform data obtained under a certain operating condition can be compared to the waveform data of the normal condition to grasp the trend of the waveform data of the certain operating condition. From the result of the comparison between the waveforms of the normal condition and the certain operating condition, a diagnostic guidance, which indicates the cause of a failure and a way of tackling it, can be displayed.